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Nanomechanical properties of α-synuclein amyloid fibrils: a comparative study by nanoindentation, harmonic force microscopy, and Peakforce QNM.

Sweers K, van der Werf K, Bennink M, Subramaniam V - Nanoscale Res Lett (2011)

Bottom Line: For nanomechanical measurements, we used single-point nanoindentation, in which the AFM tip as the indenter is moved vertically to the fibril surface and back while the force is being recorded.We also used two recently developed AFM surface property mapping techniques: Harmonic force microscopy (HarmoniX) and Peakforce QNM.We discuss the relative merits of these three methods for the determination of the elastic properties of protein fibrils, particularly considering the differences and difficulties of each method.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanobiophysics Group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands. k.k.m.sweers@utwente.nl.

ABSTRACT
We report on the use of three different atomic force spectroscopy modalities to determine the nanomechanical properties of amyloid fibrils of the human α-synuclein protein. α-Synuclein forms fibrillar nanostructures of approximately 10 nm diameter and lengths ranging from 100 nm to several microns, which have been associated with Parkinson's disease. Atomic force microscopy (AFM) has been used to image the morphology of these protein fibrils deposited on a flat surface. For nanomechanical measurements, we used single-point nanoindentation, in which the AFM tip as the indenter is moved vertically to the fibril surface and back while the force is being recorded. We also used two recently developed AFM surface property mapping techniques: Harmonic force microscopy (HarmoniX) and Peakforce QNM. These modalities allow extraction of mechanical parameters of the surface with a lateral resolution and speed comparable to tapping-mode AFM imaging. Based on this phenomenological study, the elastic moduli of the α-synuclein fibrils determined using these three different modalities are within the range 1.3-2.1 GPa. We discuss the relative merits of these three methods for the determination of the elastic properties of protein fibrils, particularly considering the differences and difficulties of each method.

No MeSH data available.


Related in: MedlinePlus

Peakforce QNM images in liquid and ambient conditions. Height (A, C) and corresponding elasticity maps (B, D) recorded with Peakforce QNM. Panels A and B are recorded in liquid (setpoint is 14 nN) and C and D in ambient conditions (setpoint is 16 nN). The fibrils have in these images an average modulus of elasticity of 3 GPa and mica between 6 and 7 GPa. Image size is 2 × 2 μm.
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Figure 4: Peakforce QNM images in liquid and ambient conditions. Height (A, C) and corresponding elasticity maps (B, D) recorded with Peakforce QNM. Panels A and B are recorded in liquid (setpoint is 14 nN) and C and D in ambient conditions (setpoint is 16 nN). The fibrils have in these images an average modulus of elasticity of 3 GPa and mica between 6 and 7 GPa. Image size is 2 × 2 μm.

Mentions: The surface property mapping technique Peakforce QNM is able to image the sample both in ambient conditions and in buffer solution. Figure 4 shows height images and the corresponding elasticity maps obtained with Peakforce QNM of α-synuclein fibrils, obtained in buffer (Figure 4A, B) and in air (Figure 4C, D). These images were obtained with a high setpoint of around 15 nN and show that for both liquid and ambient conditions the height and elasticity ranges which can be obtained with Peakforce QNM are similar. However, this large setpoint causes the fibrils to break, especially in liquid, see Figure 4A.


Nanomechanical properties of α-synuclein amyloid fibrils: a comparative study by nanoindentation, harmonic force microscopy, and Peakforce QNM.

Sweers K, van der Werf K, Bennink M, Subramaniam V - Nanoscale Res Lett (2011)

Peakforce QNM images in liquid and ambient conditions. Height (A, C) and corresponding elasticity maps (B, D) recorded with Peakforce QNM. Panels A and B are recorded in liquid (setpoint is 14 nN) and C and D in ambient conditions (setpoint is 16 nN). The fibrils have in these images an average modulus of elasticity of 3 GPa and mica between 6 and 7 GPa. Image size is 2 × 2 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211334&req=5

Figure 4: Peakforce QNM images in liquid and ambient conditions. Height (A, C) and corresponding elasticity maps (B, D) recorded with Peakforce QNM. Panels A and B are recorded in liquid (setpoint is 14 nN) and C and D in ambient conditions (setpoint is 16 nN). The fibrils have in these images an average modulus of elasticity of 3 GPa and mica between 6 and 7 GPa. Image size is 2 × 2 μm.
Mentions: The surface property mapping technique Peakforce QNM is able to image the sample both in ambient conditions and in buffer solution. Figure 4 shows height images and the corresponding elasticity maps obtained with Peakforce QNM of α-synuclein fibrils, obtained in buffer (Figure 4A, B) and in air (Figure 4C, D). These images were obtained with a high setpoint of around 15 nN and show that for both liquid and ambient conditions the height and elasticity ranges which can be obtained with Peakforce QNM are similar. However, this large setpoint causes the fibrils to break, especially in liquid, see Figure 4A.

Bottom Line: For nanomechanical measurements, we used single-point nanoindentation, in which the AFM tip as the indenter is moved vertically to the fibril surface and back while the force is being recorded.We also used two recently developed AFM surface property mapping techniques: Harmonic force microscopy (HarmoniX) and Peakforce QNM.We discuss the relative merits of these three methods for the determination of the elastic properties of protein fibrils, particularly considering the differences and difficulties of each method.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanobiophysics Group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands. k.k.m.sweers@utwente.nl.

ABSTRACT
We report on the use of three different atomic force spectroscopy modalities to determine the nanomechanical properties of amyloid fibrils of the human α-synuclein protein. α-Synuclein forms fibrillar nanostructures of approximately 10 nm diameter and lengths ranging from 100 nm to several microns, which have been associated with Parkinson's disease. Atomic force microscopy (AFM) has been used to image the morphology of these protein fibrils deposited on a flat surface. For nanomechanical measurements, we used single-point nanoindentation, in which the AFM tip as the indenter is moved vertically to the fibril surface and back while the force is being recorded. We also used two recently developed AFM surface property mapping techniques: Harmonic force microscopy (HarmoniX) and Peakforce QNM. These modalities allow extraction of mechanical parameters of the surface with a lateral resolution and speed comparable to tapping-mode AFM imaging. Based on this phenomenological study, the elastic moduli of the α-synuclein fibrils determined using these three different modalities are within the range 1.3-2.1 GPa. We discuss the relative merits of these three methods for the determination of the elastic properties of protein fibrils, particularly considering the differences and difficulties of each method.

No MeSH data available.


Related in: MedlinePlus